This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Optical methods that quantitatively separate absorption from scattering in turbid media are typically based on strategies that employ spatially and/or temporally modulated light sources. Both spatial and temporal modulation methods employ either real- or frequency-domain measurements in conjunction with model-based analyses. Most of these methods determine spatially averaged absorption and scattering values in tissue volumes near source and detector optical fibers placed in contact with the tissue, limiting the mapping capability of these techniques to one or a series of discrete measurement locations. One strategy that overcomes the limits to spatial mapping employs the spatial frequency domain and is based on the projection and analysis of periodic structured illumination patterns.